A chilled beam, more particularly, an active chilled beam, is a combined discharge register and heat exchanger that is provided in the ceiling of a conditioned space. The discharge register portion receives primary air that is conditioned to satisfy the latent load of the conditioned space, the ventilation requirements of the conditioned space, and some of the sensible load of the conditioned space. The sensible load is further satisfied in an active chilled beam by cooling primary and some secondary conditioned space air using the heat exchanger portion. The primary air is ejected through nozzles to create the secondary flow by induction thereof. Water is pumped through the heat exchanger portion at a temperature that is above the dew point to prevent the heat exchanger portion causing condensation.
Active chilled beams provide benefits in areas with substantial sensible cooling and heating requirements and relatively mild ventilation requirements. This is because they can save on the primary air requirements associated with traditional VAV systems. Active chilled beams also are associated with low noise levels.
In addition, due to the very low noise levels of active chilled beams buildings that have special noise levels requirements are good candidates. Finally zones where there is high concern about indoor environment quality are ideal candidates as the conditioned spaces are provided with proper ventilation air and humidity control at all times and under all load conditions.
Generally, active chilled beams in a zone are supplied by a respective air handling unit. The air handling units can provide temperature-neutral latent load reduction by, for example, a desiccant wheel. The water temperature can be controlled by a control valve regulating flow through the heat exchanger portion from a water supply to a return. Water temperature can also be controlled by varying the rate of flow on either side of a heat exchanger that removes heat from the water.